2006 Volvo S60 2.5 AWD, Endless search of problem

[Unownreality]

I have a live scanner/feed tool for my obd. What readings should i be paying attention to? Should i post all the readings on here as well?

[Unownreality]

I recorded a video showing how my volvo acts visually and with live data. The video is split into 2 seperate videos because I ran out of space nearing the end.

The first segment is start-up, and live data on idle. The second half is running at 2k-3k RPM, but as you can see in the video, its impossible to hold at any single point. If anything jumps out at you, I'd love to know as I really don't know what to look for.

Part 1:
Part 2:

[EngineeringBloke]

You have a significant lean condition detected by the O2 sensors resulting in the ECM adding extra fuel.
Also you have a wide fluctuating engine load.

At idle, the LTFT is 25%, but the STFT is also 25% and that STFT is the adjustment on top of the LTFT setting, so the full trim is 50%.
Your cat temperature was 300 C but rose to 700 C which is really high. I wonder if the O2 sensor seeing extra air is coming into the exhaust system from a leak, and the extra fuel added is being burned in the cat rather than in the engine.

You may have multiple issues.
- I suggest you get the exhaust inspected.
- At 2000+ RPM, STFT goes to zero, this is often indicative of a vacuum leak.
- The MAF may be under reporting air resulting in a lean mix seen at the O2 sensor.
- I wonder about the throttle body too.

What chemical did you use to clean the MAF that is in use, and how did you clean it? Or are you using a new MAF?
Is it a Bosch or Volvo MAF?

[Unownreality]

I used a fuel body cleaner, to clean the fuel body. CrC throttle amd fuel body cleaner. It was pretty gunked up, but it got it looking very nice.

MAF is a bosch.

I do believe im burning fuel in or near the cat with the big changes in exhaust pressure. Every once in a while, ill get a large puff of air through the exhaust. Im now also getting the occasional backfire into the intake.

It doesnt seem like its clogged, but not all the fuel is being combusted. Fuel body position seemed high at idle (12ish %)

[XC70Rider]

Yes those are that are in my volvo. Even at $45 a pop, dont want to change whats not broken.

Did you install new Bosch fuel injectors or reinstall the old fuel injectors with missing pintle caps?

Running that lean with backfiring you have a massive vacuum leak.

Using a brush to clean the MAF could of damaged it. Do you have any current DTCs?

[mrbrian200]

Top video, idling hot... Looks like the throttle plate is sitting at 12% open on a hot engine at idle. Which would be very lean. Throttle plate should be 5-8% tops after it settles down after the rev at start. Rising RPM is the fuel trims richening the mix I suspect. If the throttle plate were sitting where it's supposed to, there would be no need to feed it more fuel and idle speed would stay down.
I'm leaning back toward the throttle body. Everything else may be just be fallout from a major vacuum leak, but in this case it's not from a loose hose or bad gasket - it's getting past the throttle plate.

I'm not sure how long it takes for buildup on the injectors to start causing problems less the pintle caps. Could be tens of thousands of miles and may or may not be playing into your issues at hand.

[Unownreality]

I kept the old fuel injectors, but they are sitting in with no pintle caps. I'm planning on taking care of the pintle cap issue in the morning. I'll take pictures of the fuel rail when I disassemble tomorrow.

I've done smoke tests with "cigars" and I can't seem to find any leaks post-MAF. I'm hoping the air leak is from the lack of pintle caps keeping the o-rings from sealing properly.

If it is the Throttle body, I'll try resetting by pulling the cord, turning to position 2 on the ignition, back to off, and replug. From the research I've done with faulty throttles, that can sometimes do the trick. So far, I've gotten it down to 11%, but it can open up to 100% (assuming, I've seen it at 80 without flooring it).

[Unownreality]

Update: i pulled the fuel rail, put on the pintle caps, and inspected the injectors again. No build up at all. Reinstalled them, and did some driving. The stall problem i initally had is now back. Stalling about 25% i come to a complete stop.

[mrbrian200]

If it gets lean enough it will stall. I suspect you are having the same problem I did 3 years ago-- The TB gets 'sticky' at multiples of 6-7% which corresponds to the spacing/size of the teeth on the internal gears inside the TB.

They wear the most in the first few teeth/part throttle range under 30% because, except when accelerating from a stop, that's where the TB operates most of the time while maintaining speed/cruising.

6-7% is where it should be at a normal warm idle. 12.9 tells me it's sticking open on the first 'worn tooth', probably when you're seeing long and short term fuel trims add up to ~50%. The next 'step' in the gearing would stick in the range betweeen 18-21% which simply may be too lean to stay running. Have a passenger watch your scan tool while you drive it around to confirm this is what is happening.

[Unownreality]

Driving around, the throttle body never drops below 12.8%. It does seem to act normal qhen opening but wont drop to that magic 7-8% ever. Starting to be convinced its the throttle body causing the issue.